Apparatus for minimizing friction



E. KLAHN March 23, 1937.

APPARATUS FOR MINIMIZING FRICTION AND VIBRATION OF ROTOR ELEMENTSOrigiggl Filed April 25, 19:3

' 32 iilfsi INVENTOR- EMIL KLA nu BY I AITORN EY- Reissued Mar. 23, 1937UNITED STATES PATENT OFFICE APPARATUS FOR MNIIWIZING FRICTION JohannaMargaret Percival,

Summit, N. J.

Original No. 2,054,055, dated Serial No. 667,814, April 25, for reissueDecember 11, 1936,

13 Claims.

The invention relates to the reduction of friction in bearingconstructions and to the production of substantially vibrationless rotorelements.

Among the objects of the invention is the provision of means forintroducing a compressed gaseous medium between a rotor element and anassociated stator element in such a. manner that a substantiallyfrictionless rotation therebetween is assured without any otherlubrication, since all metal-to-metal contact therebetween iseliminated.

Another object of the invention resides in the particular and novelmanner of distributing the compressed gaseous medium whereby adifferential thrust is obtained thereby enabling rota-.

tion of the rotor element, the said gaseous medium serving also toaccomplish the substantial elimination of friction between the two saidelements.

Still another object of the invention resides in the novel method ofbalancing a rotor element by the use of the novel bearing construction.

In practicing the invention, provision is made for a stator and amovable or rotor element which are associated with each other forrelative rotation; and one of these elements constitutingthe supportingmember is provided with an axialduct for the admission of a suitablecompressed gaseous medium and distribution of the same in the novelmanner in the form of a separating layer or film between the surfaces ofthe two elements, which are in contact when at rest, whereby frictionbetween the two coacting surfaces is eliminated for all practicalpurposes.

a To this end, a radial port affords communication from the axial ductto the uppermost portion of the periphery of the corresponding elementand discharges the gaseous medium into a preferably longitudinal exposeddistributing recess provided, adjacently the port orifice, in theperiphery of the said gas-supplying stator element. This distributionrecess under inoperative conditions is sealed under the action ofgravity upon the coacting supported member, and such recess is sodesigned that in operation the outt'flow of gaseous medium therefromshall be so restricted that there will be no equalization of pressurethroughout the space between the two elements; but, on the contrary, thepressure on the different areas of the supported element are unequal;

Moreover, the separating film develops only when the pressure of thisgaseous medium is sufficient, as applied over the area of the orifice oradministratrix,

September 8, 1936, 1933. Application Serial No.

distributing recess, to lift off or separate the supported member fromthe. supporting member, that is to say, to overcome the weight of theformer or counteract gravity action thereon.

In this connection, it is to be further understood that to secure theelimination of friction the operating pressure of the gas need be onlyslightly in excess of that required to efifect the aforesaid separationof the elements. The gaseous medium, after flowing out of the orifice ordistributing recess, is caused to flow therefrom all over the peripheryof the supporting member, expanding in the gradually enlarging spaceafforded in the slight and eccentric separation of the elements anduntil said medium arrives, for example, at the underside of thesupporting member where provision is made for exhausting the spentgaseous medium to the atmosphere as at the ends of the supported member.Intermediate discharge of the expanding gaseous medium may also beeffected, if desired, by providing additional discharge grooves orchannels angularly displaced from the distribution recess.

By providing a distribution recess or groove designed, as hereinafterdescribed, to distribute a greater volume of the gaseous medium from oneside than upon the other, it is possible to set up a differentialpressure or thrust which may be caused to impart rotational movement tothe rotor element of the bearing device, the speed of rotation beingproportional to the pressure of the gaseous medium supplied in excess ofthat required to eliminate metal-to-metal contact of the coactingmembers.

Furthermore, where the bearing device is likely to be subjected toconsiderable external vibration, cushioning pockets for receiving andpocketing a portion of the gas may be provided over the periphery of thesupporting member, or the supported member, or both.

The device herein described is peculiarly adapted for accomplishing thepractically perfect balancing of rotors such, for example, aspropellers, fly wheels, shafts, armatures, gyroscopes, turbine rotors,etc., as well as scale arms and the like. a

The nature of the invention, however, will best be understood whendescribed in connection with the accompanying drawing, in which:

Fig. 1 is a fragmentary plan view of a balance apparatus, as oneembodiment of my invention, a portion thereof being shown inlongitudinal section.

Fig. 2 is a transverse section taken on the line 2-2, Fig. 1 of thedrawing.

Fig. 3 is a plan view of the supporting member of the novel bearingdevice, and illustrates a modification.

Fig. 4 is a transverse section therethrough taken on the line 4-4, Fig.3 of the drawing.

Fig. 51s a similar transverse section illustrating a modification.

Referring to the drawing, more especially Figs. 1 and 2 thereof, theparticular embodiment of the invention shown therein is for the purposeof effecting a proper balancing, say of a rotor such as a propellermember having the hub l0 and arms H and I2, the hub for this purposebeing shown as keyed to a rotor element as the sleeve or bushing l3adapted to be supported by the stator element or supporting member, asthe spindle ll. The latter is rigidly supported, for example, on a framemember If! through a connection l6 suitable for supplying the gaseousmedium under the required pressure. This madium is arranged, through theconnection It, to

be introduced axially to the stator [4 which, to this end, is providedwith an axial duct ll. The duct H in turn communicates with a radiallydisposed port l8 extending to the uppermost portion of the periphery ofthe stator l4, and terminates preferably in a distribution groove l9provided longitudinally in the periphery thereof and adjacent theorifice of the port. The area of this groove is so proportioned inconformity with the pressure of the gas supplied through port l8 thatthe supported member, in this instance the rotor l8 which, when there isno gas applied, rests under its own weight over the said groove to sealoff the same, will be only slightly raised by the intervening jet ofgas, as indicated in Fig. 2 of the drawing (on a greatly exaggeratedscale). This causes the supplied gas to be distributed over theperiphery of stator l4 and in opposite directions from the groove l9therein, the action then being independent of any increase of pressurewhich would merely cause additional volume and increase of flow betweenthe two elements.

Having so located on the supported member or bushing I3 the selectedrotor to be balanced, the air is introduced under suflicient pressure toeffect the slight separation of such bushing from the supporting memberor spindle l 4 on which it rests. Thereupon, the selected rotor willassume or remain in a position with its heaviest portion at the lowestpoint, or in the plumbline. The rotor is then corrected or compensatedin the usual manner until it remains stationary in any position in whichit is set, thereby bringing its center of gravity coincident with itscenter of rotation and so eliminating vibration of the rotor when inuse. By this method a perfect balance of a rotor element, such as apropeller, fly wheel, etc., can be accomplished and by an inexperiencedoperator; whereas in all cases in which mechanical bearings heretoforeknown are employed for the purpose of balancing a rotor, accuratebalancing thereof is impossible due to the limitation resulting from theinherent friction of such bearings.

In the construction of the stator and rotor elements, it is desirablethat careful machining of the same is securedso that but a fewthousandths of aninch difference in diameters shall be had, say, .002inch, in order that the flow of the escaping gas be sufliciently impededand retarded to provide time for proper expansion toward the dischargeand to effect the necessary aforesaid unequal pressure distribution inthe intervening space. As a specific example, it has been found thatthis difference in diameters between a stator and a rotor, in which theformer is of diameter, should desirably be less than 0.003 of an inchand between 0.001 and 0.0015 has been found to give excellent results.

Furthermore, if the difierence is excessive, an unnecessary anduneconomical volume of gas is required for operation. The amountsupplied need be sufficient only to allow an appreciable lubricatingflow through a diameter differential of say at least 0.00075 which isabout the lowest possible from a practical economical machiningstandpoint.

The orifice of the radial port is preferably also of relatively smalldiameter, say in the present instance .01 inch, for if the same be mademuch larger, undue and objectionable vibration of the parts results.

Also, for economical use of the gas and efl'ective operation, theexpansion must be gradual, and it will be observed, Fig. 2 of thedrawing, that, under these conditions where the separation at theorifice is but slight, an eccentric relationship exists between thesupporting and supported member whereby the space between their twocoacting surfaces is of progressively increasing volume toward theunderside so that the pressure thereof progressively drops.

This decrease in pressure may be further enhanced by the provision of aplurality of transverse expansion grooves 20 located in the underside ofthe periphery of the supporting member transversely to its length. Forexhausting the spent gas from the under side of the said supportingmember, a longitudinal outlet groove 2| is provided therein at rightangles to grooves 20, the same extending to the ends of the supportedmember or bushing l3 which is held on the supporting member 14 bysuitable collars 22 and 23, as shown in Fig. 1. The latter, to assist inthe discharge of the spent gas may be provided with recesses 24 and 24',respectively, in their inner \faces and of a diameter exceeding that ofthe supporting member, said pockets serving at the sametime as pneumaticend-thrust bearings.

Instead of the transverse expansion grooves indicated in Figs. 1 and 2,expansion of the gas may be enhanced by the provision of a series oflongitudinal grooves 25, Figs. 3 and 4 of the drawing, and locatedbetween the distributing groove 26 of the supporting spindle 21, thesaid intermediate grooves as well as the bottom groove 28 continuinglongitudinally of the periphery of the spindle to the ends of thecoacting supported member 29 and serving thereby also as an outlet ordischarge grooves for affording a greater pressure at the upper half ofthe spindle than at the lower half. It will be understood, of course,that all grooves and like expedients may be eliminated as the gas in anyevent will exhaust itself through the space at the ends of the supportedmember.

Where the coacting bearing elements are subjected to external vibration,a plurality of recesses or pockets 30 may be provided in the surface ofthe spindle 21 (or its coacting supported member, or both) to pocket aportion of the gas and affordthereby pneumatic cushions, serving toprevent metal-to-metal contact.

If it be desired to effect rotation of the rotatable element or rotormember of the novel combination, the gas supplied for substantialelimialso to provide the motive force for this rotation.

Thus, reference being had to Fig. of the drawing, the supporting spindleis provided with the axial duct 36 for supplying the gas under apressure sufficient not only for the elimination 5 of friction asaforesaid, but to provide also the motive power. The duct 36, as in thepreviously described embodiments,.communicates through a radial port 31with a distributing groove 38 provided longitudinally of the peripheryof the spindle, and expansion ducts 39 may be provided longitudinallyover the remaining surface of the spindle as in the embodiment shown inFigs. 3 and 4.

However, with respect to the distributing groove 38, provision is madeforeifecting a differential discharge or distribution of the gas whenthe supported member 29 separates from its coacting supporting member.Thus, the one wall 40 of the groove 38 is constructed of a greater 20height than the opposite longitudinal wall 4| (which in the presentinstance is shown as of zero height) so that a greater outflow of thesupplied gas at the side corresponding to wall 4| will result; or, theorifice 26, Figs. 3 and 4, may be displaced to one side of the medianline of its groove 26, or both expedients may be resorted to. Thiscauses an unequal pressure distribution and opposite unequal thrusts,resulting in the rotation of the supported member 29 in the direction ofthe arrow; and, at the same time, the gas thus distributed serves toeliminate substantially friction between the coacting elements ashereinbefore described. It will be understood, of course, that if thespeed of rotation is to be increased, it is necessary merely to providethe gas under a greater pressure; and that this will in nowise affectthe friction elimination.

What is claimed:

1. A bearing device, comprising a rotor ele- 40 ment and a statorelement, one of said elements constituting a supporting member for theother element with a difference in diameters not exceeding a fewthousandths of an inch, the said stator being provided with alongitudinally extending duct for supplying a gas under pressure andwith a lateral discharge port on its periphery in communication withsaid duct, and means on the opposite side of said stator member fromthat of said port for relieving the pressure of such gas below that ofsuch inlet pressure whereby gas discharged from the port will separatethe two elements and be distributed therebetween with its volumeincreasing progressively toward the under side of the stator and willexhaust freely into the atmosphere.

2. A bearing device, comprising a rotor element and a stator element,one of said elements constituting a supporting member for the otherelement with a difference in diameters not exceeding a few thousandthsof an inch, and the said stator being provided with a longitudinallyextending duct for supplying a gas under pressure and with a lateraldischarge port on its periphery in communication with said duct, wherebygas discharged from the port will separate the two elements and bedistributed therebetween with its volume increasing progressively towardthe under side of the stator, a discharge groove being providedlongitudinally in the periphery of said stator along its under side andextending respectively to the ends of the rotor and which dischargegroove is in free communication with the external atmosphere.

3. A bearing device, comprising a rotor element and a stator element,one of said elements constituting a supporting member for the otherelementwith a difference in diameters not exceeding a few thousandths ofan inch, and the said stator being provided with a longitudinallyextending duct for supplying a gas under pressure and with a lateraldischarge port in its periphery in communication with said duct, wherebygas discharged from the port will separate the two elements and bedistributed therebetween with its volume increasing progressively towardtheunder side of the stator, and collars on the supporting member atopposite ends of the rotor for retaining the latter against endwisemovement, said collars being provided over their respective innersurfaces with recesses for the spent gas.

4. A bearing element, comp-rising a rotor element and a stator element,one of said elements constituting a supporting member for the otherelement with a difference in diameters not exceeding a few thousandthsof an inch, and the said stator being provided with a longitudinallyextending duct for supplying a gas under pressure and with a lateraldischarge port in its periphery in communication with said duct, and theperiphery of the stator having a longitudinal groove receiving gas fromsaid port and of an area relative to the pressure of the gas to lift therotor slightly off the stator whereby gas discharged from the port willseparate the two elements and be distributed therebetween with itsvolume increasing progressively toward the underside of the stator.

5. A bearing device, comprising a rotor element and a stator element,one of said elements constituting a supporting member for the otherelement with a difference in diameters not exceeding a few thousandthsof an inch, and the said stator being provided with a longitudinallyextending duct for supplying a' gas under pressure and with a lateraldischarge port in its periphery in communication with said duct, wherebygas discharged from the port will separate the two elements and bedistributed therebetween with its volume increasing progressively towardthe under side of the stator, a discharge groove being providedlongitudinally in the periphery of said stator along its under side tothe ends of the rotor, and transverse expansion grooves being providedover the under surface of the stator and communicating with itslongitudinal discharge groove.

6. A bearing device, comprising a rotor element and a stator element,one of said elements constituting a supporting member for the otherelement with a difference in diameters not exceeding a few thousandthsof an inch, and the said stator being provided with a longitudinallyextending duct for supplying a gas under pressure and with a lateraldischarge port in its periphery in communication with said duct, wherebygas discharged from the port will separate the two elements and bedistributed therebetween with its volume increasing progressively towardthe under side of the stator, a discharge groove being providedlongitudinally in the periphery of said stator along its under side tothe ends of the rotor, and longitudinal expansion grooves being providedin the periphery of said stator intermediate the orifice of the port andoutlet groove.

7. A bearing device, comprising a rotor element and a stator element,one of said elements constituting a supporting member for the otherelement with a difference in diameters not exceeding a few thousandthsof an inch, and the said stator being provided with a longitudinallyextending duct for supplying a gas under pressure and with a lateraldischarge port in its periphery in communication with said duct, wherebygas discharged from the port will separate the two elements and to bedistributed therebetween with its volume increasing progressively towardthe under side of the stator, and the coacting surface of an elementbeing provided with a plurality of recesses to pocket the gas foraffording pneumatic cushions between the elements.

8. A bearing device, comprising a rotor element and a stator element,one of said elements constituting a supporting member for the otherelement with a difference in diameters not exceeding a few thousandthsof an inch, and the said stator being provided with a longitudinallyextending duct for supplying a gas under pressure and with a lateraldischarge port in its periphery in communication with said duct, and theperiphery of the stator having a longitudinal groove receiving gas fromsaid port and of an area relative to the pressure of the gas to lift therotor slightly oil the stator, said port discharging therein at one sideof the median line of the groove, whereby gas discharged from the portwill separate the two elements and be distributed therebetween with itsvolume increasing progressively toward the under side of the stator, andeffect rotation of the rotor element.

9. A bearing device, comprising a rotor element and a stator element,one of said elements constituting a supporting member for the otherelement with a difference in diameters not exceeding a few thousandthsof an inch, and the said stator being provided with a longitudinallyextending duct for supplying a gas under pressure and with a lateraldischarge port in its periphery in communication with said duct, and theperiphery of the stator having a longitudinal groove receiving gas fromsaid port and of an area relative to the pressure of the gas to lift therotor slightly off the stator and the one wall the distributing groovebeing at a level below that of the other wall thereof, whereby gasdischarged from the port will separate the two elements and bedistributed therebetween with its volume increasing progressively towardthe under side of the stator and effect rotation of the rotor elemient.

10. A bearing device, comprising a cylindrical rotor element and acylindrical stator element, the one enveloping the other and one of saidelements constituting a supporting member for the other element, theinternal diameter of the enveloping element not exceeding the externaldie ameter of the enveloped element by more than a few thousandths of aninch, and the said stator being provided with a longitudinally extendingduct for supplying a gas at its periphery and, at

one side only with a waste gas outlet angularly displaced therefrom andin communication with an area of lower pressure than that in the spacebetween said elements and which outlet is of sufficient size to preventthe equalization of air pressure within such latter space.

11. A bearing device, comprising a rotor element and a stator element,one of said elements constituting a supporting member for the otherelement with a difference in diameters not exceedinga few thousandths ofan inch, and the said stator being provided with a longitudinallyextending duct for supplying a gas at its periphery and at one side onlywith a waste gas outlet belowthelongitudinal axis of said statorelement, which is so correlated inside to the free space between thelongitudinal surfaces of said elements at the most contracted portion ofsaid space above the bottom of the inner element as to prevent thesetting up of back-pressure and thereby insuring adifferential ofpressure on the top and bottom of the inner element.

12. A bearing device, comprising a rotor element and a stator element,one of said elements constituting a supporting member for the otherelement with a difference in diameters not exceeding a few thousandthsof an inch, and the said stator being provided with a longitudinallyextending duct for supplying a gas at its periphery and at one side onlyand an exhaust duct discharging at the end of one of the elements and incommunication with a low pressure area less than the pressure betweenthe longitudinal adjacent surfaces of said element for preventingequalization of gas pressure in the space surrounding the inner elementwhereby a gradually diminishing pressure of the discharged gas may beestablished toward the unsupported Portion of the rotor member.

13. A bearing device, comprising a rotor element and a stator element,one of said elements constituting a supporting member for the otherelement with a difference in diameters not exceeding a few thousandthsof an inch, and the said stator being provided with a longitudinallyextending duct for supplying a gas at its periphery and at one side onlyand an exhaust duct discharging at the end of one of the elements and incommunication with a low pressure area less than the pressure betweenthe longitudinal adjacent surfaces of said element for preventingequalization of gas pressure in the space surrounding the inner element,whereby gas passing through the duct will separate the two members andbe distributed therebetween with a progressive increase of volume aboutthe periphery of the stator.

JOHANNA MARGARET PERCIVAL,

Administratria: of the Estate of Emil Klalm, De-

ceased.

